#2 Goldust
This one needs very little explanation. Goldust, or Dustin Rhodes, is the real-life brother of Cody Rhodes and the two did have some strong performances on WWE programming when they were both signed there. However, this relationship never felt properly explored or even acknowledged in WWE despite anticipation of a brother versus brother feud among other suggestions.
If Goldust were to join his brother's company, the storylines write themselves as we can see him appear either alongside or in opposition of his brother Cody. Additionally, this proposed move might indeed be an appealing one for an ageing Goldust who is essentially a non-factor in the WWE at the moment and hasn't been treated seriously as a performer in the company for quite some time now.
A move to AEW could rejuvenate Goldust's career, set up a number of matches fans would be keen to see and help propel the fledgeling promotion as it attempts to make a name for itself.